Method for removal of solid deposits from electrode surfaces in water disinfecting systems using electrolytic cells, and a device for use thereof

ABSTRACT

A method for removal of solid deposits from surfaces of electrodes of a DC electrolytic cell for disinfecting of water in a closed system, especially in a swimming pool, SPA or hot tub, includes simultaneous spinning the water over the electrode surfaces and electrolytic release of the deposits from the surfaces without interruption of the disinfecting process. The method further includes a) changing the polarity of the electrodes of the cell at predetermined frequency for electrochemically releasing the deposited scale from the electrode surfaces; b) circulating the water through a hydrocyclone containing a DC electrolytic cell for disinfecting of the water so that the deposits are washed off the electrodes of the cell; c) periodically removing the scale particles from a drained chamber located at the bottom of the hydrocyclone.

FIELD OF THE INVENTION

The present invention relates to water disinfecting systems, especiallyto those for swimming pools, whirlpool baths (sometimes called “Jacuzzi”and hereinafter referred to as SPA) and hot tubs. More specifically, theinvention relates to the systems of electrolytic disinfecting of waterand to a method and device for removal of calcium carbonate andmagnesium carbonate (scale) deposits from the electrode surfaces.

BACKGROUND OF THE INVENTION

Disinfecting of water in closed systems, such as swimming pools, SPA,hot tubs and the like with oxidizing substances, such as activechlorine, ozone and others, produced by electrolyzing water andinorganic salts contained therein is well known and effectively used. Itis also well known, however, that this process can be graduallyinhibited by the formation of deposits, such as scale made of calciumcarbonate and magnesium carbonate, on the electrode surfaces up tocomplete interruption of the flow of water through the electrolyticcell.

In a method disclosed by international application WO 99 16715, depositsare removed from the electrodes in the process of disinfecting of waterby the stream of the water running through the electrolytic cell. Thesuccess of this method regarding removal of the deposits is limited bythe water flow rate value. In this method, the water flow rate cannotexceed certain limit without deterioration of parameters of theelectrolysis process.

Ep 0 175 123 describes an attempt to resolve the problem created by thedeposits by regularly changing both the direction of water runningthrough the disinfecting electrolytic cell and the polarity of theelectrodes in the cell. To reinforce the effectiveness of said twofactors, the electrolytic cell is equipped with special turbulencegrate. This method, however, relates to disinfecting of water used inmedical devices dealing with small volumes of related apparatuses andlow water flow rates. Furthermore, the method requires an additionalwater storage reservoir and a complicated control circuit optionallyincluding a microprocessor.

U.S. Pat. Nos. 5,580,438 and 5,389,210 etc., by Michael R. Silveridisclose an elaborated system and devices for removal of scale de positsfrom disinfecting electrodes by use of an additional pump and movableparts that wash the deposits off the electrodes. Due to its complexity,such system increases the maintenance needs and reduces the overallreliability of the swimming pool/SPA operation.

The present invention relates to the process of disinfecting of water inclosed systems, especially water of swimming pools, SPA and hot tubs,where comparatively big volumes of water are involved. While preservingthe principle of simultaneously disinfecting the water and removingdissolved scale from the water by electrolysis, the present inventionprovides an economical and more efficient and effective method ofremoval of the deposits due to synergy effect arising from changing thepolarity of electro des of the cell and water turbulence. To achievethis effect, the electrolytic cell is placed in a hydrocyclone. In thepresent invention, the limitation imposed on water flow rate by therequirements of electrolysis is compensated by the effect of rotation ofwater and centrifugal forces arising in the hydrocyclone. This effectallows cleaning the scale deposits from the electrodes without anymovable parts, which provides an effective maintenance-free device.

SUMMARY OF THE INVENTION

The present invention provides a method for removal of solid depositsfrom surfaces of electrodes of a DC electrolytic cell for disinfectingof water in a closed system, especially in a swimming pool, SPA or hottub, by simultaneous electrolytic release of said deposits from saidsurfaces and spinning the water over said electrode surfaces withoutinterruption of the disinfecting process. The said method comprises:

-   changing the polarity of the electrodes in the electrolytic cell at    predetermined frequency for electrochemically releasing the    deposited scale from the electrode surfaces;-   circulating the water through a hydrocyclone containing said DC    electrolytic cell for disinfecting of the water so that said    deposits are washed off the electrodes of the cell;-   periodic removing the scale particles from a drain chamber located    at the bottom of the hydrocyclone.

The electrolytic cell for disinfecting of water is in flow connectionwith said swimming pool, SPA or hot tub through a multiple pipe circuitcontaining a circulation/service pump and several jet/main pumps.According to the present invention, the electrolytic cell is functioningonly if the circulation/service pump is in operation.

There are two modes of operation regarding the disinfecting of water inthe above-mentioned closed systems, based on this arrangement:

-   1) “A low voltage mode” with a voltage ranging from 2 to 6 volts DC    applied to the electrolytic cell;-   2) “A high voltage mode” with a voltage ranging from 6 to 12 volts    DC applied to the electrolytic cell.

The water disinfecting system operates in the low voltage mode only whensaid circulation/service pump is in operation. In this mode, aforesaidlow DC voltage is applied to and disconnected from the electrodes of theelectrolytic cell for respective pre-determined time periods.

In a preferred embodiment of the present invention, the electrolyticcell can be connected with the source of said low DC voltage upon anindication of a water flow sensor operatively placed after saidcirculation/service pump.

The low voltage can also be connected to the electrolytic cell upon anindication given by a coil transformer located on the phase wire of themotor of said circulation/service pump.

The high voltage mode of operation is in use when thecirculation/service pump and at least one of said jet/main pumps are inoperation. The voltage source is automatically disconnected with a fixedpredetermined delay after the last of said jet/main pumps stops. In thehigh voltage mode of operation, said high voltage is applied to theelectrolytic cell according to at least two water flow rate indicationssimultaneously given by water flow sensors operatively placed after saidcirculation/service pump and after at least one of said main/jet pumps.

The high voltage can also be applied to the electrolytic cell accordingto the indications given by coil transformers located on the phase wiresof the motors of said circulation/service pump and at least one jet/mainpump.

In these two modes of operation, the polarity of the voltage is changedwith a pre-determined frequency.

Both the low and the high voltage applied to the electrolytic cell canbe automatically regulated according to the indications of a sensor ofoxidation/reduction potential or free/active chlorine concentration.

The present invention further provides a maintenance-free deviceoperating according the aforesaid method for removal of solid depositsfrom surfaces of electrodes used in a DC electrolytic cell fordisinfecting of water in a closed system.

The said device comprises:

-   a) At least one electrolytic cell for disinfecting the water.-   b) A hydrocyclone containing said electrolytic cell and connected    with said SPA/swimming pool/hot tub through a multiple pipe circuit    having a circulation/service pump and, optionally, at least one    jet/main pump.-   c) A drain chamber located under the bottom of said hydrocyclone and    having a drain pipe with a tap for periodical removal of the solid    particles of said deposit.-   d) A system control unit operating said electrolytic cell so as the    source of constant voltage is connected to said electrolytic cell    and the polarity of electrodes of the cell is automatically changed    with predetermined frequency for separating solid deposits from the    electrode surfaces.

The electric circuit provides low voltage and high voltage operationmodes of the SPA/swimming pool/hot tub disinfecting system according tothe method of the invention.

In order to make the electrolytic cell function only if thecirculation/service pump is in operation, said control circuit isconnected to an electric output of the water flow sensor operativelyplaced after the circulation/service pump.

In order to alternately connect the electrolytic cell to and disconnectit from the source of the low voltage of 2 to 6 Volts DC for respectivepre-determined time periods, said control circuit is connected to atimer.

In order to connect the electrolytic cell to the source of high voltageof 6 to 12 Volts DC and disconnect the cell from said voltage with afixed pre-determined delay after the last of said jet/main pumps stops,the system control unit is connected to a timer and an electric outputof a water flow sensor operatively placed after the circulation/servicepump, as well as to electric outputs of water flow sensors operativelyplaced after said jet/main pumps.

Said control circuit is also connected to an electric output of areduction/oxidation potential sensor or free chlorine sensor forregulating the voltage level of the electrodes according to theconcentration of the free/active chlorine or the REDOX potential in thewater of said closed system.

In a preferred embodiment of the present invention, the system controlunit of the device according to the invention can also be connected tothe coil transformers located on the phase wires of thecirculation/service pump motor and at least one of said jet/main pumps'motors in order to apply low or high voltage to said cell.

If required, said control circuit can comprise only electronic elements.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described in detail by FIGS. 1-4. Thisdetailed description is not intended to limit the scope of the presentinvention, but only to illustrate the preferred embodiment.

FIG. 1 illustrates a scheme of the device according to the presentinvention.

FIG. 2 illustrates a SPA pipe circuit including said device.

FIG. 3 illustrates modes of low/high voltage control by means of waterflow sensors or transformer coils.

FIG. 4 illustrates modes of free-chlorine concentration control by meansof a REDOX-meter or a free-chlorine concentration sensor.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 illustrates electrolytic cell (5) placed in hydrocyclone (19).Hydrocyclone (19) is connected with the multiple pipe circuit SPA (16)through connections (20), (21). Building up the deposits on electrodesof the cell is effectively prevented owing to the synergy effect arisingfrom two different effects taking place in the hydrocyclone:

-   a) the effect of electrolytic release of the deposits from the    surfaces of said electrodes by changing polarity of the electrodes    at a pre-determined frequency;-   b) the effect of washing the deposits off the electrode surfaces due    to circulating the water through said hydrocyclone and spinning the    water over the electrodes. The spinning is caused by conical surface    of hydrocyclone (19).

Solid particles (23) of the deposits are collected in drain chamber (22)located at the bottom of hydrocyclone (19) and are periodically removedtherefrom through drain connection (24).

FIG. 2 illustrates the complete operation system of disinfecting ofwater in the SPA.

The system relates to two operation modes of the SPA, depending on needsof its users and requirements to the water chlorinating level.

The low voltage operation mode is brought into effect when onlycirculation pump (3) is in operation.

The high voltage operation mode proceeds if at least one of jet/mainpumps (11) is functioning alongside circulation/service pump (3).Jet/main pumps (11) pump water from filter (17) to the jets of SPA (16)through suction pipe line (18) and pressure pipe line (26).

In order to supply 2-6 Volts DC to electrolytic cell (5) over the lowvoltage operation mode, water flow sensor (1) or transformer coil (2)activate switch (4) through timer (8) (See FIG. 3). Timer (8) and switch(4) are parts of the system control unit (see FIG. 2). Over the highvoltage operation mode, electrolytic cell (5) is connected to a sourceof DC voltage of 6 to 12 Volts to increase the level of chlorinating ofwater. To provide this connection, above-mentioned water flow sensor (1)or a transformer coil (2) alongside any of water flow sensors (9) ortransformer coils (10) activates switch (12), also relating to saidsystem control unit, and switches off switch (4) (See FIG. 3).

2 hours after the last of pumps (11) stops, timer (13) turns off switch(12) and closes switch (4) to resume said low voltage mode (See FIG. 3).

Electrolytic cell (5) can be connected to a source of DC voltage only ifpermanent flow of water through said cell is provided. To meet thisrequirement, the system control unit disconnects electrolytic cell (5)from any source of DC voltage upon a minimum indication given by waterflow sensor (1) operatively placed after circulation/service pump (3)(See FIG. 2).

Said polarity change of the electrodes of electrolytic cell (5) isallowed every 20 minutes over each of aforesaid two modes by switches(7) activated by timer (6) (see FIG. 3). Timer (6) and switches (7) alsorelate to said system control unit.

In another preferred embodiment, the level of chlorinating of water isregulated by means of a REDOX-meter (14) or a free-chlorineconcentration sensor (15). REDOX-meter (14) or free-chlorineconcentration sensor (15) signals to controller (25), which activatesswitches (4) or (12) according to pre-determined cutoff values.

1. A method for removal of solid deposits from surfaces of electrodes ofa DC electrolytic cell used for disinfecting water circulated in aclosed system without interruption of the disinfecting process, saidmethod comprising: a. providing a hydrocyclone; b. placing said DCelectrolytic cell within said hydrocyclone: c. changing the polarity ofthe electrodes of said cell at a predetermined frequency forelectrochemically releasing said deposits from the electrode surfaces;d. simultaneously with step c, circulating the water by acirculation/service pump through the hydrocyclone containing the DCelectrolytic cell to disinfect the water and wash said released depositsoff the electrode surfaces; e. Periodically removing the releaseddeposits from a drain chamber located at the bottom of saidhydrocyclone.
 2. The method according to claim 1, wherein no voltage isapplied to the electrodes of said electrolytic cell if thecirculation/service pump is out of operation.
 3. The method according toclaim 1, wherein, in step c, a voltage is applied to the electrodes ofsaid electrolytic cell, said voltage is a low voltage ranging from 2 to6 volts DC with the polarity of said voltage being changed at thepredetermined frequency; said method further comprising alternatelyapplying said low voltage to and disconnecting said low voltage from theelectrodes in predetermined time periods, provided that thecirculation/service pump is in operation, and jet/main pumps of saidclosed system are out of operation.
 4. The method according to claim 3,wherein said low voltage is applied to the electrodes of saidelectrolytic cell according to a water flow indication given by a waterflow sensor operatively placed downstream of the circulation/servicepump.
 5. A method according to claim 3, wherein said low voltage isapplied to the electrodes of said electrolytic cell according to anindication given by a coil transformer located on the phase wire of themotor of said circulation/serving pump.
 6. The method according to claim1, wherein, in step c, a voltage is applied to the electrodes of saidelectrolytic cell, said voltage is a high voltage ranging from 6 to 12volts DC with the polarity of said voltage being changed at thepredetermined frequency, provided that the circulation/service pump andat least one of jet/main pumps of said closed system are operated orhave been in operation since the last time that the circulation/servicepump was in operation.
 7. The method according to claim 6, wherein saidvoltage is automatically interrupted with a fixed delay after the lastof said jet/main pumps stops.
 8. The method according to claim 6,wherein said high voltage is applied to the electrodes of theelectrolytic cell according to at least two water flow rate indicationssimultaneously given by water flow sensors operatively placed downstreamof said circulation/service pump and at least one of said jet/mainpumps.
 9. A method according to claim 6, wherein said high voltage isapplied to the electrodes of said electrolytic cell according toindications given by coil transformers located on the phase wires of themotors of said circulation/service pump and at least one of saidjet/main pumps.
 10. The method according to claim 1, wherein, in step c,a voltage is applied to the electrodes of said electrolytic cell, anamplitude of said voltage being regulated by means of anoxidation/reduction potential sensor or free/active chlorineconcentration sensor to be in the range of 2-12 volts DC, according to apre-determined setting for the REDOX potential or free chlorineconcentration.
 11. The method according to claim 10, wherein saidvoltage is adjusted to be from 2 to 6 volts DC with the polarity of saidvoltage being changed at the predetermined frequency and is alternatelyapplied to and disconnected from the electrodes in predetermined timeperiods, provided that the circulation/service pump is in operation, andjet/main pumps of said closed system are out of operation.
 12. Themethod according to claim 10, wherein said voltage is adjusted to befrom 6 to 12 volts DC with the polarity of said voltage being changed atthe predetermined frequency, provided that the circulation/service pumpand at least one of jet/main pumps of said closed system are operated orhave been in operation since the last time that the circulation/servicepump was in operation.
 13. The method according to claim 1, wherein saidclosed system is selected from the group consisting of a swimming pool,SPA and hot tub.
 14. The method according to claim 1, wherein the wateris introduced tangentially into the hydrocyclone and withdrawn axiallytherefrom.
 15. The method according to claim 1, wherein saidhydrocyclone and the electrodes of said DC electrolytic cell containedtherein are kept stationary relative to a pool of water of the closedsystem through which said water circulates.
 16. A maintenance-free waterdisinfecting device having a capability of removing solid deposits fromsurfaces of electrodes of a DC electrolytic cell used for disinfectingwater in a closed system which includes one of SPA, pool and hot tub,said device comprising a. at least one said DC electrolytic cell fordisinfecting the water, b. a hydrocyclone containing said electrolyticcell and being connected with said one of SPA, pool and hot tub througha multiple pipe circuit having a circulation/service pump and at leastone jet/main pump; c. a drain chamber located under the bottom of saidhydrocyclone and having a drain pipe with a tap for periodical removalof solid particles of said deposits; d. a system control unit operatingsaid electrolytic cell to selectively connect a source of a constantvoltage to the electrodes of said electrolytic cell and to automaticallychange the polarity of said voltage on the electrodes with apre-determined frequency for releasing the solid particles of saiddeposits from the electrode surfaces.
 17. The device according to claim16, wherein said system control unit is connected to a timer and to anelectric output of a water flow sensor operatively placed downstream ofsaid circulation/service pump in order to alternately connect anddisconnect the electrodes of the electrolytic cell to and from thesource of said voltage which is a low voltage ranging from 2 to 6 voltsDC for predetermined time periods.
 18. The device according to claim 16,wherein said system control unit is connected to a timer and an electricoutput of a water flow sensor operatively placed downstream of saidcirculation/service pump and to electric outputs of water flow sensorsoperatively placed downstream of said at least one said jet/main pump inorder to connect the electrodes of the electrolytic cell to the sourceof said voltage which is a high voltage ranging from 6 to 12 volts DCand to disconnect the electrodes of said cell from the source of saidvoltage with a fixed delay after the last of said at least one jet/mainpump stops.
 19. The device according to claim 16, wherein said systemcontrol unit is connected to an electric output of a reduction/oxidationpotential sensor or free chlorine sensor in order to regulate saidvoltage of the electrodes according to the concentration of free/activechlorine in the water of said closed system.
 20. The device according toclaim 16, wherein said system control unit is connected to a coiltransformer located on the phase wire of the motor of thecirculation/service pump in order to apply said voltage which is a lowvoltage ranging from 2 to 6 volts DC to the electrodes of theelectrolytic cell.
 21. The device according to claim 20, wherein saidsystem control unit is connected to coil transformers located on thephase wires of the motors of the circulation/service pump and said atleast one jet/main pump in order to apply said voltage which is a highvoltage ranging from 6 to 12 volts DC to the electrodes of said cell.22. The device according to claim 16, wherein said system control unitcontains only electronic elements.